Congressional Democrats insisted today that the House of Representatives immediately probe whether heat waves and droughts — and the threat of more to come — jeopardize the nation’s electric supply.

The push by Reps. Henry Waxman of California and Bobby Rush of Illinois — both top Democrats on the House Energy and Commerce Committee — came on the heels of a Washington Post article highlighting how “drought and rising temperatures are forcing water managers across the country to scramble for ways to produce the same amount of power …with less water.”

Waxman and Rush cited what they said are growing indications that increasingly frequent heat waves and droughts tied to climate change are hurting the electricity sector.

This is especially true with nuclear plants that often rely on local water sources to cool reactors. Droughts can cause water levels to dip too low to be used in some cases; in others, the local water temperature rises above levels deemed safe for cooling.

“The record-breaking heat and drought conditions are forcing power plant operators to operate hydroelectric projects with less water and to cool fossil and nuclear power plants with less water,” the lawmakers said in a letter to top House Energy and Commerce Republicans.

Among evidence the lawmakers cite:

Dominion Power shut down a nuclear reactor at its Millstone Power Station in Connecticut in August when water needed to cool the reactor became too warm at 76.7 degrees.

Exelon Corp. saw the cooling water pond at its Braidwood reactors in Illinois reach 102 degrees this summer, higher than the 98 degree maximum allowed at the site.

During the summers of 2010 and 2011, the Tennessee Valley Authority curtailed activity at its Browns Ferry nuclear reactors in Alabama because the river used for cooling became too hot.

The Midwest Independent System Operator had to shut down one of its reactors this summer when a cooling water source dipped below the intake pipes used to deliver it to the site.